If he truly believes the released data were fake, he can for sure publish his results. It’s not unusual for scientists to have different views on certain subjects. Some journals even have specific discussion sections for contradictory results. Finding the truth and correcting scientific records is also an achievement.
And at least, in the filed of biology/medicine, there are journals accepting “second first” papers, for example https://elifesciences.org/articles/30076 .
And quit a lot of publications are not grand breaking ideas. Incremental improvements can also be published.
I don’t understand your friend’s rationale to abandon the whole project he already started and didn’t want to find the truth and prove his theory (maybe it’s a different field thing).